National Academies finds breakthrough on citrus greening unlikely

The Sunshine State is the No. 2 producer of oranges in the world after Brazil. Citrus grown in Florida primarily ends up in juice form on kitchen tables throughout the world. Hurricane Irma in September 2017 affected the state's citrus crop in a big way. Before Irma the total impact of citrus on Florida’s economy was $8.6 billion a year.
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The owner of southeast Lee citrus groves say they need to be able to switch to mining if the citrus industry continues to experience production issues.(Photo: NEWS-PRESS STAFF FILE PHOTO)

ST. PETERSBURG, Fla. — An organization that advises the federal government on science and technical matters has dire news for Florida's citrus industry.

In a report released Tuesday morning, the National Academies of Sciences, Engineering, and Medicine says a single breakthrough discovery for managing citrus greening in the future is unlikely. Greening has progressed from "an acute to a chronic disease throughout the state" and has caused Florida's industry a cumulative loss of $2.9 billion in grower revenues from 2007 to 2014.

According to the report, significant barriers to finding a solution still exist.

"Among them the inability to culture the bacteria in the laboratory, the lack of advanced diagnostics for early disease detection, and the absence of standardized research methodology that would improve the comparability of results across studies," the report says.

Greening is spread by a tiny invasive bug called the Asian Citrus Psyllid, which carries bacteria that are left behind when the psyllid feeds on a citrus tree's leaves.

Andrew Meadows is a spokesman for Florida's Florida Citrus Mutual, the marketing and lobbying arm for the state's citrus growers. He called the report frustrating, but he wasn't particularly surprised by the findings.

"We would love to have a silver bullet," he said. "But you have to adapt to what you have."

Meadows said that before Hurricane Irma in 2017, citrus growers had found ways to work around the disease, at least temporarily, and were expecting a rebound year. But the hurricane devastated the crop. Initial estimates pegged the year's crop yield at the lowest since 1942.

The image of Florida oranges is iconic around the world. Florida typically grows the most oranges in the U.S., and most are used for juice. In the 2016-2017 growing year, the value of the crop was $800 million.

Oranges cover the ground at one of Paul Meador's Valencia groves near Immokalee on Thursday, Sept. 28, 2017. "As you can see from the amount of fruit on the ground, this is more than an average crop," Meador said. "It was a banner year. If we had delivered this crop, we probably would have been back in the black for the first time in a very long time." Nicole Raucheisen/Naples Daily News

Rotten oranges cover the ground and embankments at one of Paul Meador's Valencia groves near Immokalee on Thursday, Sept. 28, 2017. Floodwaters caused the crop to float and accumulate in certain parts of the property. Nicole Raucheisen/Naples Daily News

Martin Mason, 75, examines his citrus trees on his farm in Fort Denaud on Friday, Sept. 29, 2017. Many of his crops were severely damaged by Hurricane Irma. Mason is an experienced citrus grower who bought this farm in 2011. "This was the year I was about to break even, and now I'm back at square one," he says. Dorothy Edwards/Naples Daily News

Martin Mason, 75, examines his citrus trees on his farm in Fort Denaud on Friday, Sept. 29, 2017. Many of his crops were severely damaged by Hurricane Irma. Mason is an experienced citrus grower who bought this farm in 2011. "This was the year I was about to break even, and now I'm back at square one," he says. Dorothy Edwards/Naples Daily News

Martin Mason, 75, examines his citrus trees on his farm in Fort Denaud on Friday, Sept. 29, 2017. Many of his crops were severely damaged by Hurricane Irma. Mason is an experienced citrus grower who bought this farm in 2011. "This was the year I was about to break even, and now I'm back at square one," he says. Dorothy Edwards/Naples Daily News

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Growers have been using a variety of stopgap measures to work around the disease, Meadows said. Nutritional supplements for the trees, psyllid control, and water quality are among the temporary solutions, as is planting with greening-tolerant rootstocks.

The psyllid isn't native to Florida but is believed to have arrived from someone who perhaps unknowingly brought a slip of a tree from Asia. The bug was first spotted in the state in 1998, and some think it then spread during hurricanes and storms. Greening was first spotted in 2005. There isn't a cure, and no country has ever successfully eradicated it.

Greening slowly kills a citrus tree. The infection reveals itself first with mottling of leaves, then stunting of shoots, gradual death of branches and eventually, small, deformed fruits with bitter juice.

The Citrus Research and Development Foundation, a $124 million state citrus-industry initiative, asked the Academies to review its research, and that's how the report came about.

The National Academies are private nonprofit institutions that were chartered to provide analysis and advice to the nation on science, technology and health.